1. Field of the Invention
The present invention relates to an apparatus for removing protective films of a printed wiring board in which a dry film provided with a protective film is used during the manufacturing of printed wiring boards. A protective film is removed before the film is developed.
2. Description of the Related Art
In some steps for manufacturing printed wiring boards, dry film resists are used for etching, plating or solder masking. In etching and plating resists, patterns are formed by using resist ink by means of a screen printing method. In recent years, there has been a great demand for lighter, thinner, shorter, and smaller electronic apparatuses, and there has been a tendency for the patterns of printed wiring boards to be finer. Dry film resists having excellent resolution have come to be widely used, and the amount that is used is increasing sharply.
In the step for manufacturing printed wiring boards by using such dry film resists, a dry film resist which is cleaned and polished in preliminary treatment is bonded and applied to a laminated sheet by a laminator. Then, the dry film resist is developed through an exposure step, and etching or plating is performed. The dry film resist used as a solder mask is cured and fixed after being developed, and then sent to the next step.
Dry film resists used in this manner are usually formed of a three-layer structure consisting of a base film, a resist and a cover film. In the above-described step for bonding and applying a dry film resist to a laminated sheet by means of a laminator, while the cover film is being taken up on a roller, it is bonded and applied in a state in which the resist surface is directly in contact with the surface of the laminated sheet. At this time, the base film remains on the topmost surface of the sheet. The base film is usually a thin polyester film, and protects resists (hereinafter the base film of the dry film resist will be referred to as a protective film). Although the exposure step can be performed on a dry film resist provided with a protective film, the protective film must be removed because if it remains, it will be an obstacle to the next development step. For this reason, hitherto, the protective film has been peeled off manually after the exposure step and thereafter put into a development apparatus.
As the number of fine patterns of a printed wiring board has increased, there has been an increase in the use of printed wiring boards in manufacturing dry film resists having excellent resolutions. On the other hand, costs have increased because manual labor is required to peel off the protective films, and defects occur when inexperienced users handle it improperly. Therefore, there has been a great demand for the automation of peeling off protective films.
Recently, automatic peeling apparatuses for peeling off protective films have been released on the market against such a background. One example is the apparatus shown in FIGS. 6 and 7, in which a sheet travelling in the direction of the arrow is stopped at a start position of a protective film 7 of a dry film resist 6 applied onto a printed wiring board 5. A hold such as a notch is made by a cutter blade or a needle 8. Next, air is blown from an air blowout opening 9 while the board 5 is being moved in the direction of the arrow to remove the protective film. Another example is an apparatus, as shown in FIG. 8, in which an adhesive tape 10 is applied to the surface of the protective film 7 of the dry film resist 6 applied onto the printed wiring board 5. The protective film 7 is peeled off with the adhesive tape 10 and are taken up by a take-up roller 11.
However, the method of the above-mentioned former apparatus of the prior art has a problem in that if the start notch position varies, the protective film cannot be completely removed. Also, when this type of automatic apparatus temporarily is stopped in order to reposition, the operation speed is limited, and an obstacle to achieving high speed of the line arises. Problems may also arise, for example, because variations in the position at which a dry film is applied may make the start notch position improper, preventing the dry film from being completely removed, or since air is blown, cut pieces of the film may adhere, causing defective development. Mass-production thereof is difficult.
Although the problems of peeling off protective films have been somewhat reduced by the method shown in FIG. 8, because the adhesive tape used for peeling off protective films which is consumed in proportion to the amount of the protective film is discarded after use, a large amount of materials are used, increasing manufacturing costs. There is another problem, for example, when dry film resists of different sizes are processed, it is necessary to adjust the position each time they are processed, causing the automatic apparatus to stop for the setup, thus lowering the overall operating ratio of the line and increasing costs.